Electrical characterization and modeling of Negative Bias Temperature Instability in p-MOSFET devices

Negative Bias Temperature Instability (NBTI) is a serious reliability concern for digital and analog CMOS circuits. This tutorial will focus on electrical characterization and modeling of defects created during NBTI stress in p-MOSFET devices. After a brief introduction, proper choice of stress bias will be discussed such that unwanted bulk-trap generation is avoided during accelerated stress test. Various types of interface defects will also be discussed and the one associated with "NBTI" will be identified. Several electrical characterization techniques such as drain current, charge pumping, and low voltage SILC will be discussed next, and the advantages and drawbacks of each of these techniques will be discussed. The importance of measurement delay and its severe impact on NBTI time evolution will be specially highlighted. NBTI generation and recovery results obtained (using a delay-free measurement) respectively during stress & post-stress will be presented for a wide range of samples (different EOT, nitridation type and dose). It will be shown that NBTI generation and recovery can be fully explained using the well-known Reaction-Diffusion model for interface-traps. The impact of NBTI recovery on DC versus AC lifetime will also be discussed.

Souvik Mahapatra

Souvik Mahapatra received his Ph.D. in Electrical Engineering from Indian Institute of Technology, Bombay (IITB), India in 1999. From 2000 to 2001 he was at Bell Laboratories, Lucent Technologies, Murray Hill, NJ, USA. From 2002 he is with the Department of Electrical Engineering, IITB, where he is presently an Associate Professor. His research interests are electrical characterization of defects in dielectric-semiconductor interfaces; hot-carrier and bias temperature instability in CMOS devices; high-k and novel dielectrics for CMOS; and Flash EEPROMs. He has published more than 50 papers in refereed international journals and conferences, was invited to speak at several major international conferences including the IEDM and has worked as a reviewer for many international journals and conferences.